Process for blending of ink used in counterfeit detection systems

ABSTRACT

In the method for associating source information with a substrate, which includes providing at least one latent marking agent that emits a signal at an emission wavelength in response to being irradiated with infrared radiation at an excitation wavelength, wherein the signal is at least a portion of the source information; and affixing the at least one latent marking agent to the substrate, a process for providing an ink with a viscosity for effective printing of the source information on the substrate. The at least one latent marking agent includes an inorganic pigment. In some embodiments of the method, the latent marking agent must be exposed to ultraviolet radiation before it can emit a signal in response to infrared irradiation.

This application is a continuation-in-part of application Ser. No.09/458,850, filed Dec. 10, 1999.

FIELD OF THE INVENTION

This invention relates to the field of authentication and counterfeitdetection, and more specifically to processes for blending of ink usedin systems employing narrow bandwidth marking and detection technologyfor authentication and/or counterfeit detection.

BACKGROUND OF THE INVENTION

The issues of authentication and counterfeit deterrence can be importantin many contexts. Although it is apparent that authenticating money isimportant, authentication and avoidance of counterfeiting can also beimportant in many less obvious contexts. For example, improvedverification and counterfeiting prevention mechanisms would be veryuseful in, for example, verifying the contents of shipping containers,verifying the source of goods, etc. Counterfeit products are, bydefinition, unauthorized copies of a product, its packaging, labeling,and/or its logo(s). Attractive targets for counterfeits are items withsignificant brand equity or symbolic value, where the cost of productionis below the market value.

In the commercial manufacturing world, it is not uncommon forcounterfeit or otherwise unauthorized goods to be manufactured,distributed, and sold in direct competition with authentic goods.Counterfeit articles can so closely resemble genuine goods thatconsumers readily confuse the counterfeit articles with the authenticarticles. In other circumstances, the manufacturer segments the worldmarket for different sales and distribution practices, so that the“counterfeit” goods may be essentially identical to authorized goods.Further, in many instances, a manufacturer produces goods under licensefrom an intellectual property owner, and thus sales outside the terms ofthe license agreement are also “counterfeit.”

A wide variety of attempts have been made to limit the likelihood ofcounterfeiting. For example, some have tried to assure the authenticityof items by putting encoded or unencoded markings thereon (e.g., anartist's signature on his or her painting). Unfortunately, as soon asthe code is broken and/or the markings can be replicated, this methodbecomes worthless for authentication purposes.

U.S. Pat. No. 5,592,561 discloses an authenticating,tracking/anti-diversion, and anti-counterfeiting system that can trackvarious goods. The system includes a control computer, a host computer,a marking system, and a field reader system, which are all compatibleand can be physically linked via data transmission links. Anidentifiable and unique mark is placed on each good, or on materials outof which the goods are to be made, which enables subsequent inspection.The marks or patterns include areas where a marking agent is applied inan encrypted pattern and areas where it is not applied. The pattern canbe scanned or captured by a reader and deciphered into encoded data. Theentry can then either be compared directly to a set of authentic entrieson a database or decoded and compared to a set of data on the centrallylocated host database. The marking system provides control overimprinting, allowing a limited number of authorized codes to be printedbefore re-authorization is required. Monitoring of the marked goods isfacilitated by including a unique encrypted pattern having, for example,a unique owner identifier, a unique manufacturer identifier, a uniqueplant identifier, a unique destination identifier, and time and dateinformation.

U.S. Pat. No. 5,574,790 discloses a multiple-reader system forauthentication of articles based on multiple sensed fluorescentdiscriminating variables, such as wavelengths, amplitudes, and timedelays relative to a modulated, illuminating light. The fluorescentindicia incorporates spatial distributions such as bar codes asdiscriminating features, to define a user-determined and programmableencryption of the articles' authentic identity.

U.S. Pat. No. 5,289,547 discloses a method for authenticating articlesincluding incorporating into a carrier composition a mixture of at leasttwo photochromic compounds that have different absorption maxima in theactivated state and other different properties to form theauthenticating display data on the article, subjecting the display datato various steps of the authenticating method, activating allphotochromic compounds, preferential bleaching of less than all of thephotochromic compounds, and/or bleaching of less than all of thephotochromic compounds, and subsequent examination of the display datafollowing the various activation and bleaching steps by verifying meansto enable authentication.

U.S. Pat. No. 5,974,150 discloses an anti-counterfeiting system whereinan authentication certificate affixed to a product is impregnated withdichroic fibers containing a fluorescent dye. Dichroic polymer fibersmay also form part of the product to be authenticated. In order todetermine if the imprinted code corresponds to the certificate itself,the fiber pattern, which is completely random, is illuminated by a lightand read by a scanner. The resulting pattern is then compared to theencoded pattern to determine authenticity.

U.S. Pat. No. 5,212,558 discloses an encoding system wherein aconfidential image is recorded on a substrate using invisible ink. Theinvisible ink emits visible light having a wavelength of about 360-380nm when irradiated with light having a wavelength of 250 nm.Unfortunately, such a system is easily compromised by viewing theinvisible ink with a black light, which is readily available to thepublic.

Similarly, U.S. Pat. No. 5,939,468 discloses jet ink compositionssuitable for producing marks on objects that are invisible to theunaided eye and are visible only when excited by exciting radiation inthe preferred wavelength region of from about 275 nm to about 400 nm.

U.S. Pat. No. 5,093,147 discloses a method for providing intelligiblemarks that are virtually invisible to the unaided eye on the surface ofan article. The invention is based on a jet ink containing an organiclaser dye that is poorly absorptive in the visible range of about 400 to700 nm, is absorptive of radiation in the near infrared range of atleast 750 nm, and fluoresces in response to radiation excitation in theinfrared range at a wavelength longer than that of the excitingradiation. Thus, the marks remain invisible to the naked eye afterexcitation.

Thus, there remains a need for a system and method for controlling,enabling, and directing marking of goods during the manufacturingprocess and enabling detection/cross-validation of the marks so that thegoods are uniquely identified and tracked throughout the stream ofcommerce. In addition, there remains a need for a method and system formarking such that the markings are not readily reproducible anddetectable with commonly available devices and so that the markingscontain sufficient information for product authentication,identification, and tracking. There also remains a need for a systemthat can be readily altered periodically to hinder counterfeiting.

All references cited herein are incorporated herein by reference intheir entireties.

SUMMARY OF THE INVENTION

The invention relates to a process for providing an ink with a viscosityand homogeneous mixture for effective printing. In the method forassociating source information with a substrate, which method includesproviding at least one latent marking agent that emits a signal at anemission wavelength in response to being irradiated with infraredradiation at an excitation wavelength, wherein the signal is at least aportion of the source information; and affixing the at least one latentmarking agent (e.g., an inorganic, upconverting pigment) to thesubstrate, there is further provided a process which comprisesdispersing an inorganic, upconverting pigment during manufacture of theink, producing an ink with the appropriate viscosity for effectiveprinting of the source information.

Also provided are substrates marked in accordance with the inventivemethod.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the invention are particularly suitable for marking goodsduring the manufacturing process and enabling detection/cross-validationof the marks so that the goods are uniquely identified and trackedthroughout the stream of commerce. The markings, which preferablycontain source information sufficient to enable product authentication,identification, and tracking, are not readily reproducible and/ordetectable with commonly available devices.

Although the invention is particularly suitable for marking productsand/or product containers, the invention is suitable for markinginformation on any substrate which would benefit from having suchinformation encoded thereon in a latent format. Thus, the invention isalso suitable for marking substrates such as, e.g., collectibles, money,legal documents, tickets, credit cards, etc. Non-limiting examples ofmaterials from which suitable substrates can be made include paper,wood, synthetic polymers and metals.

The substrate is marked with a latent marking agent. The expression“latent marking agent” denotes a material that emits a detectable signalonly after being activated. The expression “latent marking agent”encompasses invisible inks and pigments. It is particularly preferredthat the latent marking agent be activated by electromagnetic radiation(EMR), preferably narrow bandwidth EMR (defined herein as EMR not morethan 10 nm in width), more preferably EMR having a bandwidth of 5 nm orless, even more preferably single wavelength EMR. In embodiments, theactivation or excitation wavelength is preferably at least 900 nm. Infurther embodiments, the activation or excitation wavelength is 915 nmto about 990 nm and/or 1550 nm to 1800 nm.

The EMR is preferably provided by a laser. In embodiments, the laser isa component of a detection apparatus dedicated to the task of screeningsubstrates for latent marks of the invention. The apparatus can includefeatures and components generally known to those of ordinary skill inthe art. See, example, U.S. Pat. No. 4,540,595. Thus, the system caninclude a transport means for transporting the items to the readingmeans, which includes a source of radiation having the appropriatewavelength and intensity. The reading means includes a photodetectorwhich reads the fluorescent emission. If necessary, the system caninclude optical filters to eliminate or minimize undesired radiation,and any pattern recognition circuitry appropriate to the particular codepatterns recorded.

Non-limiting examples of materials suitable for use as latent markingagents include rare earth metals, such as, e.g., europium, dysprosium,samarium or terbium, combined with a chelating agent, such as, e.g., anorganic ligand, to form a biketonate, acetonate or salicylate.Additional examples include yttria phosphors, inorganic phosphors, CibaGeigy Cartax CXDP and UV visible Eccowhite series from Eastern Color andChemical. The marking agent preferably comprises an inorganic pigment,and in certain embodiments, the marking agent is free of organic dyes.The selection of the marking agent is largely dictated by the desiredexcitation wavelength and emission wavelength. In certain embodiments,it is preferred that the excitation wavelength be longer than theemission wavelength.

The method for affixing the marking agent to the substrate is notparticularly limited. The term “affix” as used herein is intended todenote a durable (but not necessarily permanent or unremovable)association between the marking agent and the substrate. Preferably, theassociation between the marking agent and the substrate is sufficientlydurable to remain functionally intact through the stream of commerce.The marking agent can be affixed to the substrate directly (e.g., viaadsorption and/or absorption) or indirectly (e.g., via an adhesive).

The marking agent is preferably provided in a marking composition.Marking compositions generally comprise a marking agent and a solvent,with the marking agent provided at a concentration of about 2 to about10 grams/liter of solvent, depending upon the marking agent used.Preferred solvents include methyl ethyl ketone, ethanol and isopropanol.A solvent soluble resin, such as a Lawter resin, can be used if themarking agent is smaller than two microns to avoid precipitation of themarking agent for solution.

The marking compositions can further comprise additives, stabilizers,and other conventional ingredients of inks, toners and the like. Inembodiments, various varnishes or additives, such as polyvinyl alcohol,Airvol 203 and/or MM14 (Air Products and Chemicals, Inc., Allentown,Pa.), propylene carbonate, Joncry wax varnishes, and Arcar overprintvarnishes, can be added to the marking composition to reduce absorptioninto the substrate and ensure that the marking agent remains on thesurface of the substrate.

Suitable marking means include, e.g., printers, including inkjet,flexographic, gravure and offset printers, pens, stamps, and coaters.

In a particularly preferred embodiment, the marking agent is luminescentpigment Z, K, S, ZH and/or GE (available from Stardust Material, NewYork, N.Y.), which is dispersed in an aqueous or organic varnish at a 2%to 5% ratio and applied to a substrate via printing or coating. Thismark visibly fluoresces when exposed to a specific infrared light range.The illuminated color can vary depending upon the type of pigmentutilized.

The illuminated color can also vary when used in conjunction with acolored plastic film or a translucent colored coating or varnish. Thecolored translucent layer can be printed or laminated on top or underthe marking agent. The amounts of possible illuminating colors arevirtually endless due to the numerous different translucent coloredlayers available.

When used in conjunction with the translucent colored layer, onespecific marking agent can give virtually endless different illuminatingcolors, when excited by the appropriate EMR.

In embodiments, a first latent marking agent is adapted to emit a firstsignal at a first emission wavelength after being irradiated withinfrared radiation at a first excitation wavelength, and a second latentmarking agent is adapted to emit a second signal at a second emissionwavelength after being irradiated with infrared radiation. The infraredradiation which excites the second latent marking agent to fluoresce canbe the same as or different from the infrared radiation which excitesthe first latent marking agent. In either case, the first emissionwavelength and the second emission wavelength differ, preferably by atleast 5 nm, more preferably by at least 50 nm. These embodiments areuseful, e.g., to provide multiple or redundant levels of protection orauthentication, wherein authorized users having low-level clearance candetect only the first signal and are not informed of the second signal,whereas users having a higher level clearance are aware of, and canverify the presence of the second signal.

Such a system guards against security breaches from within anorganization.

The signal emitted by the latent marking agent is preferably afluorescent emission. In certain embodiments, the emission wavelength isabout 915 nm to about 1800 nm. In certain embodiments, the signal is afluorescent emission at a visible wavelength.

Thus, products can be authenticated through the stream of commerce byirradiating any marking agent affixed to the product with EMR of apredetermined excitation wavelength and monitoring a predeterminedemission wavelength for a signal, confirming the presence of the latentmarking agent on the substrate.

In embodiments, the monitoring is accomplished by a detector exclusivelytuned to the emission wavelength. The expression “exclusively tuned”indicates that the detector detects only a narrow band of wavelengthswithin ±5 nm of the emission wavelength.

In certain embodiments, the latent marking agent must be exposed toultraviolet radiation before it can emit the signal in response to beingirradiated with infrared radiation. These embodiments can be useful fora variety of purposes, including demonstrating that a document has beenphotocopied, since photocopiers expose originals to ultravioletradiation.

A product package can be marked with a first marking agent designed toemit fluorescent radiation at a first emission wavelength detected bythe detector specifically focused on the first emission wavelength.

After a period of time, counterfeiters may figure out how to duplicatethe authentication certificate, making it advisable to alter theauthentication protocol periodically or after there is a suspicion thatthe certificate has been compromised. The instant invention provides forsuch a strategy. For example, the exciting radiation generating meanscan be replaced or tuned to another wavelength and a different markingagent can be used to provide a signal differing from the compromisedsignal. If the original marking agent is used along with the updatedmarking agent, counterfeiters who have compromised the original signalmay not realize until it is too late that the original signal has beenreplaced by an updated signal.

The invention will be illustrated in more detail with reference to thefollowing Examples, but it should be understood that the presentinvention is not deemed to be limited thereto.

EXAMPLE Flexographic/Gravure Ink

1. Disperse Stardust Materials Product Z (CAS 68585-88-6) at a ratio of2% to 5% in a solution of Polyvinyl Alcohol, water and 0.5% to 2%Surfynol 104PG surfactant with standard mixing equipment.

2. Pass mixture through a wet micronizer to reduce the pigment size tobetween 3 microns to 8 microns.

3. Then wetting agents, dispersing agents and color dyes or pigments(omit if colorless is desired) are added to the mixture.

4. Adjust viscosity by either increasing water content or adding aviscous PVA MM14 additive.

5. Once the mixture has ideal viscosity and suspension of solids, thenthis mixture or ink is ready to print by standard flexographic/gravurepress.

6. Print ink on a white or clear substrate such as paper or film viaflexographic/gravure printing press.

To the naked eye, the printed ink will have no noticeable differencethan any other ink. When the printed ink is excited at a wavelength of980 nm, which is delivered by a hand-held laser apparatus, a noticeablecolor will fluoresce, and when the apparatus is removed, the ink willappear as before. If no colored dye or pigment is added to the ink, thecolor will be a bright glowing green, with red dye/pigment the colorwill be a bright glowing light, and with black dye/pigment the colorwill be green. When the laser apparatus is used in total darkness, thefluorescence will appear brighter. When the same ink is excited at 1550nm, a different color will fluoresce (in colorless it will appearyellow).

In a further preferred embodiment of the present invention, thefollowing testing was performed: Fifteen percent of inorganic,upconverting pigment with a mean particle size of 2.3 um was dispersedvia a high speed mixer during the manufacturing process of flexographicink, available as Rub & Reveal™ from Nocopi Technologies, Inc.

The ink has a high solids content (35% to 55%); thus, adding e.g., 15%of an upconverting pigment to the ink would create a very viscous, highsolids ink which would provide inadequate printing. In order to make awell-dispersed ink with the appropriate viscosity, the upconvertingpigment should be mixed during the making of the ink. The ink containstwo components (leucodye and Lewis acid activator); when both arescratched/rubbed together or heat is applied, a color appears. Bothcomponents are made separately with a wet micronizer (reduced particlesize), and then mixed together, in order to create the final ink. Theratio of Lewis acid activator to leucodye in the ink is about 2:1. Giventhe upconverting pigment is relatively hard and abrasive, prematurecolor activation can occur if it was dispersed via high sheer mixer intothe ink, with both components present. In order to avoid this problem,from about 5-15% upconverting pigment was dispersed via a high speed airmixer with the Lewis acid activator, after it has been wet micronized;the use of about 15% upconverting pigment is particularly preferred. Theupconverting pigment does not require particle size reduction; 2.3 um isa suitable size for a flexographic ink. Leucodyes are more sensitive topremature color activation when mixed with hard or abrasive pigment. Inthe final formula for the ink with upconverting pigment, the ratio of2:1 Lewis acid activator to leucodye was maintained, and the overallsolids content was only increased by about 5%.

The finished ink was then printed successfully with a small web (MarkAndy) flexographic press onto an uncoated, pressure sensitive labelstock.

In order to assess finished inks as described above, a hand held 980-nmlaser was aimed directly at the printed ink, and a green signal (550 nmto 600 nm) was visible. The printed sample was then scratched with afingernail, and the ink turned from colorless to red. A 980-nm laser wasagain directed at the scratched red ink, and a green signal was stillpresent. The two illuminated colors were different in that colors willabsorb some of the IR light and the visible color will differ from whiteor clear to a color-printed sample.

A density measurement was made with a densitometer before scratching,and after scratching the ink. In order to obtain a readable sample, IRlight was directed through the pressure sensitive label sample from theopposite side, before and after scratching. This resulted in a lighterillumination of a visible color, but still would allow for theobservation of differences.

Results are found in Table I, below:

TABLE I IR 980 nm: IR 980 nm: Scratched Red Color: No Scratch ColorScratched Red Color No IR C 0.37 0.41 0.25 Y 0.34 0.39 0.23 K 0.30 0.410.33 M 0.27 0.46 0.36 Units in Absolute Density Key: C = CYAN, Y =YELLOW, K = BLACK, M = MAGENTA

From the results noted above, it is apparent that the green color afterscratched has a stronger magenta present; (0.27 versus 0.46). A strongerblack presence is also shown; (0.30 versus 0.41). Note that if aspectrometer reading were taken comparing the percentage of reflectanceto wavelength, a more detailed difference would be observed.

The leucodye in the flexographic ink tested determines the color; in theabove example, the leucodye was a red color. Leucodyes are available toproduce a variety of colors, such as; red, blue, yellow, green, black,etc. Each leucodye has its own unique color, and it will absorb IR 980light differently, and provide different visible colors, before andafter these colors are scratched. This allows for the use of a myriad ofcolors from the “before” and “after” scratched with directed IR 980light.

Thus, the final ink contains multiple security features: When exposed to980 nm or 1550 nm light, the ink gives two different visible responses,and when scratched, the ink gives a visible color change. Furthermore,activated ink (scratched to a color) results in a different (versus notactivated) visible response when exposed to 980 nm or 1550 nm. Inpreferred embodiments, the ink displays differing visible responsesbefore and after rubbing or scratching the substrate containing the ink,when the substrate is exposed to light with wavelengths of e.g., fromabout 915 to 990 nm or 1550 to 1800 nm.

While the invention has been described in detail and with reference tospecific examples thereof, it will be apparent to one skilled in the artthat various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

We claim:
 1. In the method for associating source information with asubstrate, which includes: providing at least one latent marking agentcontaining an inorganic pigment that fluoresces at a first emissionwavelength in response to illumination at a first excitation wavelength,and also fluoresces at a second emission wavelength in response toillumination at a second excitation wavelength, wherein the first andsecond excitation wavelengths are unequal and are outside of a visiblespectrum, and the first and second emission wavelengths are unequal andare within the visible spectrum; affixing said at least one latentmarking agent to said substrate; and detecting said at least one latentmarking agent for distinguishing said substrate from other similarsubstrates, a process for providing an ink with a viscosity foreffective printing of the source information, said process comprisingmixing an effective amount of the inorganic pigment into the ink, duringmanufacture of the ink, wherein said ink displays differing visibleresponses before and after rubbing or scratching said substratecontaining said ink, when said substrate is exposed to light with awavelength of from about 915 to 990 nanometers.
 2. The method as recitedin claim 1, wherein the ink includes a leucodye and a Lewis acidactivator.
 3. The method as recited in claim 2, wherein the ratio of theleucodye to the Lewis acid activator is about 1:2.
 4. The method asrecited in claim 1, wherein from about 5-15% of the upconverting pigmentis mixed with the Lewis acid activator, during the making of the ink. 5.The method as recited in claim 1, wherein said inorganic pigment is atleast one member selected from the group consisting of chelated rareearth metals, yttria phosphors, and inorganic phosphors.
 6. The methodas recited in claim 1, wherein said ink is a flexographic ink.
 7. Themethod as recited in claim 2, wherein the leucodye determines the changein visible response.
 8. In the method for associating source informationwith a substrate, which includes: providing at least one latent markingagent containing an inorganic pigment that fluoresces at a firstemission wavelength in response to illumination at a first excitationwavelength, and also fluoresces at a second emission wavelength inresponse to illumination at a second excitation wavelength, wherein thefirst and second excitation wavelengths are unequal and are outside of avisible spectrum, and the first and second emission wavelengths areunequal and are within the visible spectrum; affixing said at least onelatent marking agent to said substrate; and detecting said at least onelatent marking agent for distinguishing said substrate from othersimilar substrates, a process for providing an ink with a viscosity foreffective printing of the source information, said process comprisingmixing an effective amount of the inorganic pigment into the ink, duringmanufacture of the ink, wherein said ink displays differing visibleresponses before and after rubbing or scratching said substratecontaining said ink, when said substrate is exposed to light with awavelength of from about 1550 to 1800 nanometers.
 9. The method asrecited in claim 8, wherein the ink includes a leucodye and a Lewis acidactivator.
 10. The method as recited in claim 9, wherein the ratio ofthe leucodye to the Lewis acid activator is about 1:2.
 11. The method asrecited in claim 8, wherein from about 5-15% of the upconverting pigmentis mixed with the Lewis acid activator, during the making of the ink.12. The method as recited in claim 8, wherein said inorganic pigment isat least one member selected from the group consisting of chelated rareearth metals, yttria phosphors, and inorganic phosphors.
 13. The methodas recited in claim 8, wherein said ink is a flexographic ink.
 14. Themethod as recited in claim 9, wherein the leucodye determines the changein visible response.